In cities large and small, automobiles are a nearly inescapable facet of contemporary life. While car use can have a number of positive benefits, there are substantial negatives as well, including congestion, crashes, risks to pedestrians and cyclists, and pollution.

A 2012 Columbia University study published in Environmental Health Perspectives, “Prenatal Polycyclic Aromatic Hydrocarbon (PAH) Exposure and Child Behavior at Age 6-7,” involved 253 mother/child pairs in New York City. The researchers monitored the subjects’ exposure to polycyclic aromatic hydrocarbons, one of the chief elements of automotive exhaust, to assess the possible links between prenatal exposure to pollutants and eventual child behavioral outcomes.

Results of the study include:

All 253 mothers were found to have some level of exposure to PAH in their daily life.

Higher levels of PAH exposure were associated with a 24% higher score of anxiety/depression for children ages 6 to 7 than those with low exposure levels.

Infants found to have elevated PAH levels in their umbilical cord blood were 46% more likely to eventually score highly on the anxiety/depression scale than those with low PAH levels in cord blood.

Exposure to PAH was found to have a similar effect to tobacco smoke exposure in terms of children’s likelihood to develop anxiety/depression.

“The results suggest an adverse impact of prenatal PAH exposure on child behavior that could impact cognitive development and ability to learn,” the researchers conclude. “Anxiety, depression and attention problems, which were associated with PAH exposure … have been shown to affect subsequent academic performance.” They suggest a variety of ways to reduce airborne PAH concentrations, including pollution controls, use of alternative sources of energy and regulatory intervention.